Progress in Satellite Attitude Determination and Control

Astrophysics and Space Science Library, 1978

IFAC Proceedings Volumes, 2014

A methodology for determining spacecraft attitude and autonomous calibration of star camera, both independent of each other, is presented. In this paper, both attitude estimation and star camera calibration is done together, independent of each other, by directly utilizing the star coordinate in image plane and corresponding star vector in inertial coordinate frame. Both radial and decentering distortion of lens accounted in the analysis. Satellite attitude, camera principal point, focal length (in pixel), lens distortion coefficients are found by a simple three step method. In the first step, camera intrinsic parameters are estimated using a closed-form solution assuming lens is distortion free. In the second step lens radial distortion coefficient is estimated by linear least squares method using the solution of the first step to be used in the camera model that incorporates only radial distortion. These steps are applied in an iterative manner until the radial distortion coefficient converges. In third step, lens decentering distortion coefficients are calculated using the estimated camera parameters and lens radial coefficient estimated in the previous steps. The whole procedure is fast enough for onboard implementation.

1996

This paper describes, for a spacecraft equipped with a wide Field-Of-View (FOV) startracker, a fa st and robust autonomous attitude determination system, consisting of a new star identification tec hnique, here developed, working with a mixed EULER-q/QUEST-2 attitude estimation algorithm, presented in . The stars identification is based on the stars angular separation. Stars are directly identified within an overall large stars catalog without using the magnitude information. A first p roposed star-pair-ID technique is based on a best fitting criterion while a second faster one uses th ree vectors of integers. A proposed "reference-star" criterion is then used for star-matching identif ication. The algorithm robustness is such that, after spikes being deleted, at least three true stars ar e still available. An overall software block diagram of the proposed system is depicted. Extensive tests have been performed and the results are shown by plots.

SpaceOps 2006 Conference, 2006

IEEE/CAA Journal of Automatica Sinica, 2019

As an important sensor in the navigation systems, star sensors and the gyro play important roles in spacecraft attitude determination system. Complex environmental factors are the main sources of error in attitude determination. The error influence of different benchmarks and the disintegration mode between the star sensor and the gyro is analyzed in theory. The integrated design of the star sensor and the gyro on the same benchmark can effectively avoid the error influence and improves the spacecraft attitude determination accuracy. Simulation results indicate that when the stars sensor optical axis vectors overlap the reference coordinate axis of the gyro in the same benchmark, the attitude determination accuracy improves.

Journal of Guidance, Control, and Dynamics, 2015

In this paper, a star tracker attitude estimation procedure with increased robustness and efficiency, using the AIM (Attitude Estimation using optimal Image Matching) algorithm, is presented and validated. The unique approach of the AIM algorithm allows us to introduce a reliable quality check which can be efficiently calculated. Unlike existing validation methods, this quality check not only detects that some of the data is unreliable, it also determines which star measurements are unreliable. These unreliable measurements can be removed from the data set and a new attitude quaternion can be calculated without having to repeat the entire AIM algorithm. This greatly improves the robustness of the attitude estimation, while limiting the computational expense. Furthermore, the structure of AIM allows us to reuse previously calculated data when the change in attitude between subsequent measurements is small. This way, the efficiency of the entire attitude estimation cycle can be increased significantly. These enhancements are validated with simulated star tracker data, which show that for pointing maneuvers, the computational cost can be reduced by more than 40% compared to the state-of-the-art procedure. The results show that the improvements significantly improve the robustness and lower the computational cost of the star tracker attitude estimation. As a consequence, the overall performance of the attitude determination and control system greatly increases. The increased efficiency of the attitude estimation could also allow the use of star trackers in smaller satellite

Advances in Estimation, Navigation, and Spacecraft Control, 2015

Attitude determination, along with attitude control, is critical to functioning of every space mission. In this paper, we investigate and compare, through simulation, the application of two autonomous sequential attitude estimation algorithms, adopted from the literature, for attitude determination using attitude sensors (sun sensor and horizon sensors) and rate-integrating gyros. The two algorithms include a direction cosine matrix (DCM) based steady-state Kalman Filter and the classic quaternion-based Extended Kalman Filter. To make the analysis realistic, as well as to improve the design of the attitude determination algorithms, detailed sensor measurement models are developed. Modifications in the attitude determination algorithms, through estimation of additional states, to account for sensor biases and misalignments have been presented. A modular six degree-of-freedom closed-loop simulation, developed in house, is used to observe and compare the performances of the attitude determination algorithms.

2000

A novel split field of view star tracker is being developed for the EO-3 GIFTS mission (2004). The camera is designed to be autonomously selfcalibrating, and capable of a rapid/reliable solution of the lost-in-space problem as well as recursive attitude estimation. Two efficient Kalman filter algorithms for attitude, camera principal point offset, and focal length estimation are developed. These algorithms make use of three axis gyros for the rate data and star camera split field-of-view line-of-sight vector measurements. To model the optics of the camera the pinhole model is used, which is found to be sufficiently accurate for most of star cameras. The relative merits of the two algorithms are then studied for estimating the principal point offset, focal length and attitude of a simulated spacecraft motion. Simulation results indicate that both algorithms produce precise attitude estimates by determining the principal point offset, focal length and rate bias; however, reliability and robustness characteristics favor the second algorithm.

An efficient Kalman filter based algorithm has been proposed for the spacecraft attitude estimation problem using a novel split-field-of-view star camera and three-axis rate gyros. The conventional spacecraft attitude algorithm has been modified for on-orbit estimation of interlock angles between the two fields of view of star camera, gyro axis, and the spacecraft body frame. Real time estimation of the interlock angles makes the attitude estimates more robust to thermal and environmental effects than in-ground estimation, and makes the overall system more tolerant of off-nominal structural, mechanical, and optical assembly anomalies.

1996

This paper describes, for a spacecraft equipped with a wide Field-Of-View (FOV) startracker, a fa st and robust autonomous attitude determination system, consisting of a new star identification tec hnique, here developed, working with a mixed EULER-q/QUEST-2 attitude estimation algorithm, presented in . The stars identification is based on the stars angular separation. Stars are directly identified within an overall large stars catalog without using the magnitude information. A first p roposed star-pair-ID technique is based on a best fitting criterion while a second faster one uses th ree vectors of integers. A proposed "reference-star" criterion is then used for star-matching identif ication. The algorithm robustness is such that, after spikes being deleted, at least three true stars ar e still available. An overall software block diagram of the proposed system is depicted. Extensive tests have been performed and the results are shown by plots.

Space Science Reviews, 2010

The work presented in this paper concerns the accurate On-Ground Attitude (OGA) reconstruction for the astrometry spacecraft Gaia in the presence of disturbance and of control torques acting on the spacecraft. The reconstruction of the expected environmental torques which influence the spacecraft dynamics will be also investigated. The telemetry data from the spacecraft will include the on-board real-time attitude, which is of order of several arcsec. This raw attitude is the starting point for the further attitude reconstruction. The OGA will use the inputs from the field coordinates of known stars (attitude stars) and also the field coordinate differences of objects on the Sky Mapper (SM) and Astrometric Field (AF) payload instruments to improve this raw attitude. The on-board attitude determination uses a Kalman Filter (KF) to minimize the attitude errors and produce a more accurate attitude estimation than the pure star tracker measurement. Therefore the first approach for the OGA will be an adapted version of KF. Furthermore, we will design a batch least squares algorithm to investigate how to obtain a more accurate OGA estimation. Finally, a comparison between these different attitude determination techniques in terms of accuracy, robustness, speed and memory required will be evaluated in order to choose the best attitude algorithm for the OGA. The expected resulting accuracy for the OGA determination will be on the order of milli-arcsec. Keywords Satellite dynamics 1 Introduction The principal feature of the Gaia astrometry mission is to accurately measure the positions, distances, space motions, and many physical characteristics of about one billion stars in

Progress in Flight Dynamics, Guidance, Navigation, Control, Fault Detection, and Avionics, 2013

This paper presents current developments of the attitude determination algorithm for Del¦-n3Xt, TU Delft next nanosatellite. Several novel quaternion ¦lters using Sun vector and Earth magnetic ¦eld measurements and rate gyro outputs are presented. The quaternion measurement matrix associated with each line-of-sight measurement is shown to be rank de¦cient. This property is exploited in order to design reduced order measurement update stages in the ¦lters. The measurement model reduction is designed such as to preserve the statistical information. The ¦lter covariance propagation can cope rigorously with the multiplicative process noises. The paper also describes the development of the Sun vector determination algorithm, which merges the outputs of 6 body-mounted four-quadrant Sun sensors. For each sensor, a simple algorithm allows Sun vector determination while avoiding the use of uncertain physical parameters. This algorithm takes into account geometrical imperfections linked to manufacturing limitations. A thorough error analysis of the photodiodes measurement outputs is carried out. A spacecraft Sun vector determination algorithm is proposed and illustrated, in the absence of Earth albedo e¨ect, via Monte-Carlo simulations and experimental validation. In addition, extensive Monte-Carlo simulations illustrate the good performances of the quaternion ¦lters using spacecraft Sun vector and Earth magnetic ¦eld measurements. The novel reduced ¦lter shows good performances in a challenging tumbling dynamics environment, where a standard additive Kalman ¦lter fails to converge.

Acta Astronautica, 2012

The Radio Aurora Explorer (RAX) is a triple CubeSat that launched on November 19, 2010. RAX was designed to study plasma irregularities in the polar lower ionosphere (80-300 km), and is the first CubeSat mission funded by the United States National Science Foundation. The scientific mission requires attitude knowledge within 51 (1Às), and a custom attitude determination subsystem was developed for the mission. The subsystem utilizes rate gyros, magnetometers, coarse sun sensors, and an extended Kalman filter, and was designed to be a simple, low cost solution to meet the attitude determination requirements. In this paper, we describe the design, implementation, and testing of the RAX attitude determination subsystem, including derivation of the determination requirements, sensor selection, the integrated hardware design, preflight sensor calibration, and attitude estimation algorithms. The paper is meant to serve as a resource for others in the small satellite and nanosatellite communities, as well as a critical reference for those analyzing RAX data. Lessons learned from the design and performance of the RAX determination subsystem will be used in future designs of attitude determination systems for small satellites and similar platforms, such as high altitude balloons and autonomous aerial vehicles.

2003

In this paper, two different algorithms are presented for the estimation of spacecraft body angular rates in the absence of gyro rate data for a star tracker mission. In first approach, body angular rates are estimated with the spacecraft attitude using a dynamical model of the spacecraft. The second approach makes use of a rapid update rate of star camera to estimate the spacecraft body angular rates independent of spacecraft attitude. Essentially the image flow of the stars is used to establish a Kalman filter for estimating the angular velocity. The relative merits of both the algorithms are then studied for the spacecraft body angular rates measurements. The second approach has an

Experimental Astronomy, 2017

We have developed a low-cost off-the-shelf component star sensor (StarSense) for use in minisatellites and CubeSats to determine the attitude of a satellite in orbit. StarSense is an imaging camera with a limiting magnitude of 6.5, which extracts information from star patterns it records in the images. The star sensor implements a centroiding algorithm to find centroids of the stars in the image, a Geometric Voting algorithm for star pattern identification, and a QUEST algorithm for attitude quaternion calculation. Here, we describe the software package to evaluate the performance of these algorithms as a star sensor single operating system. We simulate the ideal case where sky background and instrument errors are omitted, and a more realistic case where noise and camera parameters are added to the simulated images. We evaluate such performance parameters of the algorithms as attitude accuracy, calculation time, required memory, star catalog size, sky coverage, etc., and estimate the errors introduced by each algorithm. This software package is written for use in MATLAB. The testing is parametrized for different hardware parameters, such as the focal length of the imaging setup, the field of view (FOV) of the camera, angle measurement accuracy, distortion effects, etc., and therefore, can be applied to evaluate the performance of such algorithms in any star sensor. For its hardware implementation on our StarSense, we are currently porting the codes in form of functions written in C. This is done keeping in view its easy implementation on any star sensor electronics hardware.